bubble in my siphon

[msmommy4]

is it dangerous and how do i get rid of it. i increased my water flow and tilted the intake box but still this bubble

 

[der_wille_zur_macht]

It can be dangerous if it grows enough to break the siphon.

What model of overflow do you have and how much flow are you putting through it?

 

[msmommy4]

i built it myself a rubbermaid tub with a drawer insert to put my bio balls and filters in. using a hydor pump about 900gph with a check valve.

 

[graveyardworm]

What model overflow? Is it a U tube design?

 

[TheH]

Many siphon overflows will eventually accumulate bubbles until the siphon breaks. That's why some people use small pumps like the aqualifter to constantly remove any air in the tube (along with some water).

 

[msmommy4]

this is were being a newbie shows i'm not sure. it's kidds big and the tube looks like a j should i get a smaller tube

 

[hebygb]

I am having a hard time picturing this... your question is concerned with a siphon tube, but you described a sump. Can you share more about your system, display tank size, volume, type of HOB overflow.

The bubble can be bad if it increases in size, and this is likely if it appeared on its own. This is sometimes caused by having the siphon tube too low in the prefilter box, causing the opening to bottom out.. obstructing flow. Try lowering the inner box or raise the tube 1/4" by putting an eraser under the "U". There are other ways to mitigate this by installing an aqualifter pump to the top of the siphon tube and sucking the air buble out (continuously). I would make this a last resort.

 

[graveyardworm]

In my experience you need to run a hang on U/J tube type overflow at close to its max or air bubbles will accumulate. The majority of them atleast the ones I'm fmiliar with utilize a 1 inch tube. The flow through a 1 inch tube will need to be close to 600GPH depending on unions, bends, and such as the water makes its way to the sump. The check valve is going to knock the output of the pump back a bit, but not sure how much. Are you controlling the output of the pump with a valve? Do you have 1 or 2 U/J tubes?

I wouldnt raise the U tube if you do you run the risk of breaking the siphon in the event of a power failure and when the pump comes back on you will have a flood.

 

[msmommy4]

ok guys i tilted my black box and the bubble went down and out lol.

 

[thetonyage]

if it happens again just use some airline tubing and suck the bubble out

 

[hllywd]

Flow is key in keeping bubbles out of the u-tube. I used over the back overflows for many years without trouble. Your pump may be advertised as 900gph but that's almost certainly at zero head loss. With the check valve, and the height you're pumping the water the head may be reducing the flow to much less than 900gph.

Your sump should have enough room for water to siphon back in the event of a power outage, the check valve shouldn't be needed. Assuming you're not already throttling the pump back, and that you have the necessary volume available in the sump, I'd remove the check valve to see if that gives you the necessary flow to wash the bubbles through the u-tube. You can add complexity to the system by adding an aqua-lifter pump, but it's one more thing that can fail and IME if the system is set up correctly, completely unnecessary.

Tim

 

[hllywd]

if it happens again just use some airline tubing and suck the bubble out

The problem is, that only remedies the problem for the moment. Essentially that is the idea of the aqua-lifter. What happens when the aqualifter fails, or nobody is there to suck the bubble out?

Tim

 

[7designs]

I had a firefish go for a ride down my overflow, caused a huge air bubble that restricted flow enough my tank start filling up, luckily I caught it before it overfilled the DT

 

[HOZER62]

Yes as Tim said on a HOB overflow the flow from the return pump(s) is key to keep the bubbles from collecting in the top of your U tube!!!!

 

[hebygb]

That is why I said it (aqualifter) was a last resort... sucking the bubble out does not solve the condition that caused it.

It would appear that my hunch was correct that the inner box/tube relationship was not correct.

msmommy, you should be good to go from this point forward

 

[brycerb]

What about using a small powerhead that has a hookup for air line tube, like if you wanted to aerate a tank(freshwater). Hook an airline tube up from the powerhead to the top of the overflow.

 

[sjm817]

A properly designed/set up U Tube Overflow will not accumulate air and does not need high flow to keep air bubbles pushed through. I've run them with 200 GPH with no issue. Being this is a DIY, some details and pics of the setup might help. Tilting the overflow box may send a surge of water through that may push the bubble through, but it may also just build back up again.